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The effect of asymmetrical body-mass distribution on the stability and dynamics of two-degree-of-freedom quadruped bounding in place is investigated in this study. An analytical stability criterion for bounding of quadrupeds with asymmetrical mass distribution is developed. Bounding is found to be passively stable in the Hamiltonian sense when the dimensionless pitch moment of inertia of the body is less than 1 - [[beta].sup.2], where [beta] is a dimensionless measure of the asymmetry. The criterion is derived under the assumptions of infinite leg stiffness and no energy loss. With energy dissipation modeled as linear damping in the legs, simulation results show that the criterion is independent of the value of leg stiffness and a conservative estimate of the critical inertia value. Body symmetry appears to be more favorable to stable bounding than asymmetry, but only slightly so in practicality. The results show that asymmetry offers some advantages when the dynamic characteristics of bounding are compared for symmetrical and asymmetrical models. Lower stride frequency, larger vertical displacement, and smaller duty factor are obtained with this more animal-like model. Index Terms--Asymmetry, bounding, dynamics, legged locomotion, quadruped, stability.

To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-9280.2009.02447.x Byline: Sally A. Linkenauger (1), Jessica K. Witt (2), Jonathan Z. Bakdash (1), Jeanine K. Stefanucci (3), Dennis R. Proffitt (1) Abstract: ABSTRACT Perception of one's body is related not only to the physical appearance of the body, but also to the neural representation of the body. The brain contains many body maps that systematically differ between right- and left-handed people. In general, the cortical representations of the right arm and right hand tend to be of greater area in the left hemisphere than in the right hemisphere for right-handed people, whereas these cortical representations tend to be symmetrical across hemispheres for left-handers. We took advantage of these naturally occurring differences and examined perceived arm length in right- and left-handed people. When looking at each arm and hand individually, right-handed participants perceived their right arms and right hands to be longer than their left arms and left hands, whereas left-handed participants perceived both arms accurately. These experiments reveal a possible relationship between implicit body maps in the brain and conscious perception of the body. Author Affiliation: (1)University of Virginia (2)Purdue University, and (3)The College of William and Mary Article History: (R eceived 11/6/08; R evision accepted 3/5/09) Article note: Address correspondence to Sally A. Linkenauger, 102 Gilmer Hall, Charlottesville, VA 22904, e-mail: sal3g@virginia.edu.

Undesirable garment drape can be caused by incorrect positioning of the fabric before cutting, the asymmetrical body features of the wearer, inaccurately joined seams or the presence of bow and skewness in the fabric. Some research has been conducted on skewness in 3-by-1 twill-weave fabrics and on factors affecting spirality of knitted fabric. Further research, however, is required to find solutions to garment drape problems.

While bilateral symmetry is the ancestral state of molluscs, the gastropods have adopted various developmental pathways leading from bilateral symmetry to complex asymmetrical body plans. Because many of the asymmetrical organ systems are mesodermal derivatives the identification of mesodermal regulatory genes is essential for understanding how the molluscs diversified. It has been well demonstrated that Twist and Snail play a significant role in both determination and differentiation of mesoderm in a variety of organisms. Thus, using the polymerase chain reaction we have identified these two genes in the genomes of various molluscs. By in situ hybridization and Immunocytochemistry we have detected the expression of Twist and Snail in mesodermal lineages of the marine mud snail Ilyanassa obsoleta. We have also found that both of these genes are maternally expressed. Throughout the animal kingdom there are a variety of different mechanisms for mesoderm formation, and our study of teloblastic mesoderm formation in a spiralian embryo extends the body of evidence for the conservation of genes used for mesoderm formation. This body of evidence illustrates genomic antiquity in the face of developmental diversifiction.

Many animals rely on an internal heading representation when navigating in varied environments.sup.1-10. How this representation is linked to the sensory cues that define different surroundings is unclear. In the fly brain, heading is represented by 'compass' neurons that innervate a ring-shaped structure known as the ellipsoid body.sup.3,11,12. Each compass neuron receives inputs from 'ring' neurons that are selective for particular visual features.sup.13-16; this combination provides an ideal substrate for the extraction of directional information from a visual scene. Here we combine two-photon calcium imaging and optogenetics in tethered flying flies with circuit modelling, and show how the correlated activity of compass and visual neurons drives plasticity.sup.17-22, which flexibly transforms two-dimensional visual cues into a stable heading representation. We also describe how this plasticity enables the fly to convert a partial heading representation, established from orienting within part of a novel setting, into a complete heading representation. Our results provide mechanistic insight into the memory-related computations that are essential for flexible navigation in varied surroundings. Two-photon calcium imaging and optogenetic experiments in tethered flying flies, combined with modelling, demonstrate how the correlation of compass and visual neurons underpins plasticity that enables the transformation of visual cues into stable heading representations., Author(s): Sung Soo Kim [sup.1] [sup.3] [sup.4] , Ann M. Hermundstad [sup.1] , Sandro Romani [sup.1] , L. F. Abbott [sup.1] [sup.2] , Vivek Jayaraman [sup.1] Author Affiliations: (1) Janelia [...]

Sea stars of the family Asterinidae are well known for their diverse life history strategies encompassing sexual reproduction through various larval forms, while others, all multi-armed species, through clonal asexual reproduction. For at least 25 years, a geographically isolated population of the minute (radius < 7 mm) tropical Pacific fissiparous asterinid, Ailsastra heteractis, has been locally abundant in a shallow water coral rubble habitat at One Tree Island, southern Great Barrier Reef. The population biology of this sea star was investigated over 14 years to characterise its asexual reproduction through fission (splitting in half) and to determine whether a size threshold is reached for an expected switch to sexual reproduction. Fission followed by regeneration was the dominant propagation mechanism generating individuals that varied in arm number (2-7) and length (0.5-6.9 mm). Recently split individuals were present year round with regenerating individuals being the most prevalent body form. Growth rates and fission activity, as measured by mean arm length, varied among months but with no overall pattern. Analyses of arm length data based on season indicated that fission activity was lowest in autumn. There was a positive correlation between the incidence of fission and air and water temperature with a decrease in the proportion of recently split individuals in winter and an increase in summer. Fission was present in all size classes with no evidence of a switch to a larger sexual morphotype with growth. Juvenile recruitment from sexual reproduction was not evident. Extensive searches did not reveal the presence of other populations of A. heteractis. The absence of recruitment and reproductive organs coupled with a stable population demography indicates that propagation by fission is the only reproductive mechanism for the A. heteractis population., Author(s): Matthew Clements [sup.1] , Kennedy Wolfe [sup.2] , Kit Schwartz [sup.3] , Maria Byrne [sup.1] [sup.3] Author Affiliations: (Aff1) 0000 0004 1936 834X, grid.1013.3, School of Medical Sciences, The [...]

I remember one of the arguments with Jack Maxin. He was doing one of my pieces. I said, 'Don't you see these legato lines? What are you doing? Why are [...]

This paper compares the treatment of place in Beckett's fiction of the 1940s and 1950s with that of phenomenological theorizations, focusing on the relationship between subjectivity and place. It argues that, one the one hand, the subject expands place infinitely by dint of the memories and associations he brings to it, while, at the same time he is subject to place. Thus, A. N. Whitehead holds that the subject must 'conform' to the places it inhabits (qtd. in Casey 214). The paper examines this imperative through a discussion of Beckett's Texts For Nothing, and argues that the persistently renewed demand to conform to place presents Beckett's characters with an arduous task of incorporation that is ultimately beyond them: place contributes to the disintegration of the self; it is not 'a basis of ... life' (Merleau-Ponty 292). Keywords: Samuel Beckett / place / phenomenology, One would not obviously look to either Beckett or phenomenology for an understanding of place. Certainly, where the latter is concerned, the index to Dermot Moran's Introduction to Phenomenology contains [...]

ABSTRACT. Provided through the screen of a monitor, the participant's resultant center of pressure ([CP.sub.Res]) movements from a force platform device, modified the postural performance of a healthy individual. However, [...]

ABSTRACT. Terminal target-pointing error on the 1st trial of exposure to optical displacement is usually less than is expected from the optical displacement magnitude. The authors confirmed 1st-trial adaptation in [...]